The present invention generally relates to a method of printing onto a transparent receptor media, and in particular, to a method of printing an image onto an adhesive layer of a receptor media using an inkjet printer.
Printed labels are used as a convenient way to provide information or personalize items. For instance, labels on consumer items contain bar codes for inventory control, price information, or to generally identify characteristics of the goods or the source of such goods. Labels on food items contain images, such as text or graphics, that describe or portray the product.
The image on a label is typically printed onto the upper surface of the label. Since the image is exposed, it is vulnerable to moisture and scuffing, which cause the quality of the image to deteriorate. In commercial applications, the image is commonly protected by applying a clear film over the image. When the printed label is applied to the item, a border is created because the label is thick and does not blend into the background of the item. This commonly happens when a white label is applied to a colored background. While aesthetic concerns are not an issue in all applications, aesthetics are important when the user wants the labeled item to look professional. For these applications, images are printed onto transparent labels so that the label blends into the background of the item. However, the print is located on the upper surface of the label and is, therefore, still exposed to moisture and scuffing. For home uses, the image may be laminated to protect it from moisture and scuffing. However, this approach is disadvantageous since lamination increases the overall thickness of the image, adds additional steps to the process, and requires a laminating device.
Other known approaches involve using inkjet receptor compositions suitable for coating onto plastics to make the plastics inkjet receptive. For example, applications for overhead transparencies are known in the art. These are composed of transparent plastic materials such as polyester, which alone will not accept the aqueous inks and are therefore coated with receptor layers. Typically these receptor layers are composed of mixtures of water soluble polymers which can absorb the aqueous mixture from which the inkjet ink comprises, such as hydrophilic layers having poly(vinyl pyrrolidone) or poly(vinyl alcohol), as described in U.S. Pat. Nos. 4,379,804; 4,903,041; and 4,904,519. Also known are methods of cross-linking hydrophilic polymers in the receptor layers as disclosed in U.S. Pat. Nos. 4,649,064; 5,141,797; 5,023,129; 5,208,092; and 5,212,008. Other coating compositions contain water-absorbing particulates such as inorganic oxides, as disclosed in U.S. Pat. Nos. 5,084,338; 5,023,129; and 5,002,825, or those containing particulates, such as corn starch, as disclosed in U.S. Pat. No. 4,935,307 and 5,302,437.
Many of these types of inkjet receptor media, however, are less than ideal for image graphics because they include water-sensitive polymer layers. Even if subsequently overlaminated, they still contain a water-soluble or water-swellable layer, which, in time, can be subject to extraction with water and can lead to damage of the graphic and liftoff of the overlaminate. Additionally, some of the common constituents of these hydrophilic coatings contain water-soluble polymers not ideally suitable to the heat and UV exposures experienced in exterior environments, thus limiting their exterior durability. Finally, the drying rate after printing of these materials appears slow since until dry, the coating is plasticized or even partially dissolved by the ink solvents (mainly water) so that the image can be easily damaged and can be tacky before it is dry.
In the commercial setting, labels are printed by a number of processes known in the art, such as screen printing, thermal transfer printing, and inkjet printing. These processes vary dramatically in cost and the resolution of the printed images that are produced. Screen printing and thermal transfer printing are typically limited to commercial applications because they produce large numbers of identical labels and require use of expensive equipment. Screen printing is commonly used to print the transparent labels, such as those used on electronics and appliances. While the images may be screen-printed onto the reverse side of a transparent label, the adhesive is applied after the image is printed, which adds an additional step to the process, making it impractical or cost prohibitive for low-volume, non-commercial, or personal use.
Thermal transfer printing is a contact printing process where a thermally reactive ribbon is located between a thermal printhead and a print media onto which the image is to be printed. The printhead contains heating elements that are selectively energized. As the ribbon is heated, ink is transferred from the ribbon to the print media to create the printed image. Images created by thermal transfer printing are located on the upper surface of the media and are, therefore, vulnerable to moisture and scuffing. To print multi-color images, multiple printheads must be linked together, which significantly adds to the cost of the printer. The high cost of thermal transfer printers makes it economically impractical for them to be used as personal printers.
An exemplary type of thermal transfer printer is a label printer. Label printers are commonly used in grocery stores to label food items with transparent labels. An exemplary label printer is disclosed in U.S. Pat. No. 4,927,278 issued to Kuzuya et al. Label printers currently available on the market include products by Kroy LLC and Zebra Technologies.
Inkjet printers have come into general use for wide-format electronic printing for a wide and varied range of applications. Because of the simplicity of operation and economy of inkjet printers, this image process holds a superior growth potential promise for the printing industry to produce wide format, image on demand, presentation quality graphics. The components of an inkjet system used for making graphics can be grouped into three major categories: 1) computer, software, printer; 2) ink; and 3) receptor medium. The computer, software, and printer will control the size, number and placement of the ink drops and will transport the receptor medium through the printer. The ink will contain the colorant which forms the image and carrier for that colorant. The receptor medium provides the repository which accepts and holds the ink. The quality of the inkjet image is a function of the total system. However, the composition and interaction between the ink and receptor medium is most important in an inkjet system.
Inkjet printers are commonly purchased as personal printers because they are easy to use, produce high quality, color images, and are less expensive than thermal transfer printers. Inkjet printers are also available in a variety of formats that allow the user to print professional-looking banners or labels at home. Ink-jet printing is a non-contact printing process in which droplets of ink are deposited on a print media. In response to electrical signals generated by a microprocessor, fine droplets of ink are ejected onto print media such as paper, transparency film, or textiles. The ejection of ink droplets in a particular order forms alphanumeric characters, area fills, and other patterns on the print media. Images are printed onto many types of media including paper or transparent, plastic receptor media such as transparent labels or overhead transparencies. However, inkjet inks compositions are substantially aqueous-based and do not adhere to the inherently hydrophobic surface of the plastic receptor media. Therefore, to print images onto plastic receptor media, these media must first be coated with a hydrophilic film to improve the adhesion of the inkjet ink onto the media. However, since the image is printed on top of the film, the image is not protected from moisture and scuffing.
To solve the problems described above, it would be advantageous to use the inkjet printer to print an image on a hydrophobic or adhesive layer of a transparent receptor media. This would provide an affordable way of printing borderless labels that would be resistant to moisture and scuffing.
The present invention relates to a method for printing an image onto an adhesive surface of a transparent, plastic receptor media using an inkjet printer. After the image is printed, the receptor media is applied to an item, thereby personalizing the item with the image. Since the image is printed onto the adhesive surface, it is protected from moisture and scuffing after it is applied to the item. The image appears professionally printed on the item because the transparent receptor media blends with the background of the item and appears borderless. However, since the image is printed using an inkjet printer, the personalized item can be created at home or in low-quantity application settings.